New Zealand parents are being warned of the risks of carrying a baby in a sling after a newborn boy died in South Australia.
In the latest Medical Journal of Australia, two pathologists report "[the baby] was placed into a cloth sling worn under his mother's shirt and jumper and was subsequently noted by his mother to be cold and not breathing".
Authorities in several countries are investigating ways to control the risks of baby slings, which suspend the baby in soft fabric from the carrier's neck or shoulder.
The Ministry of Consumer Affairs said it had not received any reports of injuries or deaths in New Zealand linked to baby slings but it was considering developing a safety standard for them.
The pathologists, Professor Roger Byard and Dr John Gilbert, said an autopsy on the two-day-old baby found no significant abnormalities and no injuries. The cause of death was listed as undetermined, "although the baby sling was considered a risk factor".
The boy, born two weeks early, might have suffered the reduction in oxygen levels that can also occur in car baby seats, a particular risk for pre-term and low-birthweight infants, the pathologists said.
"It appears a similar situation occurs with certain slings, albeit rarely, as the soft and rounded sleeping surfaces may promote a potentially dangerous posture that impedes normal respiration.
"Sixteen deaths attributed to the use of slings have occurred in the United States and Canada, resulting in calls for mandatory standards by the US Consumer Product Safety Commission."
The pathologists said parents and carers using slings - which could cause excessive bending of the baby's neck - must be told of the risks, particularly for very young infants.
"Constant monitoring of infants in slings is advised, to ensure that the infant's head is facing outwards, with no covering of the face."
New Zealand child health researcher Dr Shirley Tonkin said slings could be dangerous if not used with great care.
"You have to have them so baby's head is kept back a little. If they wriggle and go to the side of the sling it's not good. The sort of slings that hold baby with the head forward are unsafe."
The risk was that the baby's airway could be blocked by the tongue when the chin had been pushed back by pressure on the chest when the baby was curled up.
"Baby is safest lying flat level, not even left in a car seat. The oxygen levels drop as they are left in car seats for a long time."
Dr Tonkin urged the use of commercially available foam inserts in baby car seats to stop the baby's head being pushed forward and reduce breathing problems.
The ministry said many of the risks could be avoided by practical measures such as ensuring the baby's chin could not curl down into its chest.
"Pay particular attention if you're using a sling to carry a newborn.
"Newborns do not have the necessary muscle control to open their airways and need good back support to prevent them slumping into the chin-to-chest position."
Many of the risks associated with carrying a baby in a sling can be avoided with practical measures.
When carrying a baby in a sling:
* Check that the baby can breathe.
* Do not allow the baby's chin to curl against its chest.
* Never allow the baby's head or face to be covered with fabric.
- Source: Ministry of Consumer Affairs